The heterotaxy gene GALNT11 glycosylates Notch to orchestrate cilia type and laterality.
The heterotaxy gene GALNT11 glycosylates Notch to orchestrate cilia type and laterality.
复制标题
杂质基因galnt11糖基盐凹口策划纤毛类型和侧向。
作者：
心脏异位（Htx）是一种左右（LR）身体模式或偏侧性障碍，与主要先天性心脏病相关。大多数人类Htx的病因学和机制知之甚少。在脊椎动物中，偏侧性起始于胚胎左右组织器（LRO），其中运动纤毛产生由不运动的感觉纤毛检测到的反向流，该反向流进入下游不对称信号。指定这两种纤毛类型的机制仍然未知。我们现在表明，GalNAc型O-糖基化酶GALNT 11是至关重要的，这样的决定。我们以前确定GALNT 11作为Htx患者的候选疾病基因，现在证明，在非洲爪蟾中，galnt 11激活Notch信号传导。GALNT 11在体外使NOTCH 1肽O-糖基化，从而通过增加ADAM 17介导的Notch受体的胞外域脱落或通过修饰特异性EGF重复序列来支持Notch激活机制。我们进一步开发了非洲爪蟾LRO纤毛的定量实时成像技术，并表明galnt 11介导的notch 1信号调节LRO能动和不动纤毛的空间分布和比例。galnt 11或notch 1的缺失以不动纤毛为代价增加了活动纤毛的比例，并产生了侧性缺陷，使人联想到纤毛传感器Pkd 2的丢失。相比之下，Notch过表达降低了这一比例，模拟了睫状体病，原发性睫状体运动障碍。总之，我们的数据表明，Galnt 11修改Notch，在LRO中建立运动和不运动纤毛之间的基本平衡，以确定侧性，并确定人类Htx的新机制。
Heterotaxy (Htx) is a disorder of left-right (LR) body patterning, or laterality, that is associated with major congenital heart disease. The etiology and mechanism underlying most human Htx is poorly understood. In vertebrates, laterality is initiated at the embryonic left-right organizer (LRO), where motile cilia generate leftward flow that is detected by immotile sensory cilia, which transduce flow into downstream asymmetric signals. The mechanism that specifies these two cilia types remains unknown. We now show that the GalNAc-type O-glycosylation enzyme GALNT11 is crucial to such determination. We previously identified GALNT11 as a candidate disease gene in a patient with Htx, and now demonstrate, in Xenopus, that galnt11 activates Notch signaling. GALNT11 O-glycosylates NOTCH1 peptides in vitro, thereby supporting a mechanism of Notch activation either by increasing ADAM17-mediated ectodomain shedding of the Notch receptor or by modification of specific EGF repeats. We further developed a quantitative live imaging technique for Xenopus LRO cilia and show that galnt11-mediated notch1 signaling modulates the spatial distribution and ratio of motile and immotile cilia at the LRO. galnt11 or notch1 depletion increases the ratio of motile cilia at the expense of immotile cilia and produces a laterality defect reminiscent of loss of the ciliary sensor Pkd2. In contrast, Notch overexpression decreases this ratio mimicking the ciliopathy, primary ciliary dyskinesia. Together, our data demonstrate that Galnt11 modifies Notch, establishing an essential balance between motile and immotile cilia at the LRO to determine laterality and identifies a novel mechanism for human Htx.